Neurologists call patients who are totally paralyzed "locked-in," and diagnoses of Lou Gehrig's disease or a brain-stem stroke are among the most feared of all neurological disorders. Doctors often counsel patients and their loved ones to opt against life support before becoming fully locked-in, because such a life is thought to be unbearable.

But a German neuroscientist has found a way to give voice to 11 patients around the world with a device that converts mental activity into computer commands. His experience has led him to challenge the prevailing medical assumption that locked-in lives are not worth living.